We have been developing materials to teach nonscience majors about ionizing radiation in a science literacy course. The Radiation by Inquiry Project (DUE 0942699) is uncovering problematic learned and spontaneous ideas about radiation, atoms, radioactivity, and the interaction of radiation with matter. This poster identifies some of the common ideas, our tools and strategies for getting students beyond them, and provides evidence of substantial learning. Http://www.camse.org/andy/radiation